The invention relates to a cleanable sampling valve to be incorporated into the product line supplying the samples, with a sample duct branching off from the valve housing through a sample bore, a closing element controlling the sampling through the sample bore, and a stuffing box shell which seals a valve stem that projects from the valve housing.
The invention is of importance principally for product-carrying installations and plants of the beverage industry, where it is necessary, for example, to take sterile samples from product lines for inspection and control of the process.
It is known to weld the housing of a sampling valve into the product line so as to fully integrate the sampling valve within the product line. The valve housing has an opening at its bottom for the removal of the samples, which opening can be closed by means of a closing element with a metallic seal.
The operation of the closing element is effected from the top of the sampling valve by means of a valve stem or spindle extending across the product space and being guided through a stuffing box shell to project from the valve housing, the valve spindle being thus exposed to the product and cleaning agent flowing around it within the valve housing. The valve seat is of the metallic sealing type and can therefore wholly be flame treated.
With the known valve, sterile sampling is possible if prior to the taking of the sample the sample outlet has been cleaned through the product line filled with cleaning agent and subsequently flame treated, the sampling valve being open during this procedure.
The known sampling valve does not permit repeated sampling during one product charge passage under sterile conditions. Although the known valve is equipped with a sight lantern between the valve housing and the valve actuating means, this valve--like, in principle, all other similarly constructed and equipped valves--provides no absolute safety against reinfection as the valve stem, during the switching of the valve, carries the product adhering thereto into the stuffing box area within the valve housing. The remains of product displaced in this way are as a rule incapable of being removed by automatic flow-through cleaning from the product line and thus constitute at least a possible source of reinfection.